Why is there always some waste heat in a heat engine?

In positive numbers less than 1, the zeros between the decimal point and non zero are significant

Awoman holds a book by placing it between her hands such that she presses at right angles to the front and back covers. the book has a mass of m = 1.8 kg and the coefficient of static friction between her hand and the book is μs = 0.67. no attempt 50% part (a) what is the weight of the book, fgb in newtons?

Acar travels 40m in 8 seconds find the car speed